Separating multisensory integration from unspecific warning effects in saccadic reaction time
Single Paper Presentation

Adele Diederich
School of Humanities and Social Sciences, International University Bremen

Hans Colonius
Department of Psychology, Oldenburg University

     Abstract ID Number: 41
     Full text: Not available
     Last modified: March 14, 2006
     Presentation date: 06/18/2006 8:30 AM in Hamilton Building, McNeil Theatre
     (View Schedule)

Abstract
Saccadic reaction time (SRT) to a visual target tends to be faster when auditory or tactile non-targets occur in close temporal or spatial proximity even when subjects are instructed to ignore the non-targets. When the non-target appears before the target, it may act as a general alerting or warning cue rather than as a stimulus causing crossmodal integration. The time-window-of-integration (TWIN) model for SRT (Colonius & Diederich, 2004, J Cog Neurosci) distinguishes an early, afferent stage of peripheral parallel processing followed by a compound stage of converging subprocesses. The model is extended here to permit the separation of a - spatially unspecific - warning effect from true multisensory integration. TWIN was tested in a focused attention task with visual target stimuli (LED) and auditory (white noise burst) and tactile (vibration applied to palm) stimuli as non-targets presented ipsi- or contralateral to the target at 23 different stimulus-onset-asynchronies (SOA) over a range of 700 ms. A quantitative fit of the model supports the notion that only a combination of multisensory integration and unspecific warning effects can account for the entire time course of the crossmodal mean SRT responses over SOA values in both ipsi-and contralateral configurations.